Some machine vibration monitoring devices, such as the CSI 9420 wireless vibration monitor manufactured by Emerson Process Management, collect scalar vibration trend data on a scheduled (i.e., time basis) interval ranging from one minute to one hour (device publish rate). This scalar trend data is typically published to a wireless gateway, such as the Emerson 1420 gateway, at the specified schedule interval. In addition to scalar trend data, the CSI 9420 collects analytical vibration data relevant to vibration analysis.
As the term is used herein, “analytical vibration data” refers to all forms of vibration waveforms and spectra and by-products of the vibration waveform regardless of filtering, signal processing or measurement units. Examples include but are not limited to vibration acceleration waveforms and spectra, vibration velocity waveforms and spectra, displacement waveforms and spectra, PeakVue™ waveforms and spectra, demodulated waveforms and spectra, Spike Energy waveforms and spectra, Cepstrum, spectral density plots, and frequency transfer functions.
In conjunction with machine vibration analysis software, such as Emerson's AMS Machinery Manager (MHM) software, the CSI 9420 vibration monitor has provided users the ability to store analytical vibration data retrieved from the monitor on a scheduled basis interval. However, there have been some disadvantages with the scheduled interval technique. First, scheduled acquisitions simply obtain the analytical vibration data on a scheduled basis, not based on the severity of an alert condition that may be indicated by the data. Second, depending upon when the analytical vibration data was collected, it may not provide sufficient diagnostic information to correctly identify a machine fault. This is particularly problematic with non-repetitive events. Third, transferring large amounts of data across a wireless data network, such as a WirelessHART™ network, can be very costly due to bandwidth limitations of the communication protocol and the battery consumption of the network device. Fourthly, combining these factors, if multiple machines triggered an alert simultaneously, it may not be possible to retrieve the analytical vibration data from all of the devices prior to the next scheduled measurement cycle, when the pertinent data would be overwritten by the next data set.
What is needed, therefore, is a wireless data acquisition system that acquires, retains and transfers analytical machine vibration data when scalar data indicates a possible alert condition.